What is the most important dietary instruction for a patient on isoniazid?

• A. Increase caffeine intake
• B. Do not drink beer or red wine while taking this medication because a serious adverse reaction can occur
• C. Avoid spicy foods
• D. Drink plenty of water with each dose

Answer: (B)

Alcohol should be avoided because isoniazid can cause liver inflammation and injury, and drinking alcohol greatly raises the risk of hepatotoxicity. The liver processes both substances, and using them together increases the chance of serious liver damage, which is the main safety concern with this medication. So, not drinking beer or red wine while taking isoniazid is the most important dietary guidance. If any signs of liver trouble appear—unusual fatigue, yellowing of the skin or eyes, dark urine, abdominal pain—seek medical advice promptly. Other choices aren’t as directly protective against this specific, serious risk.